This invention relates to disinfecting lenses, sucn as contact lenses. In particular, the invention relates to compositions and methods useful to quickly and effectively disinfect lenses while reducing eye irritation caused by disinfecting the lenses.
Contact lenses should be periodically cleaned and disinfected by the user to prevent infection or other deleterious effects on ocular health which may be associated with contact lens wear. Currently, there are several different conventional systems and methods which enable the user to clean and disinfect their contact lenses between wearing times. These conventional cleaning and disinfection systems can be divided into "hot" and "cold" systems. Hot systems require the use of heat to disinfect the contact lenses, whereas cold systems use chemical disinfectants at ambient temperatures to disinfect the lenses.
Within the realm of cold disinfection systems are hydrogen peroxide disinfection systems. Disinfecting hydrogen peroxide solutions are effective to kill the bacteria and fungi which may contaminate contact lenses. However, residual hydrogen peroxide on a disinfected contact lens may cause irritation, burning or trauma to the eye unless this hydrogen peroxide is destroyed, i.e., decomposed, neutralized, inactivated or chemically reduced. Therefore, destruction of the residual hydrogen peroxide in the liquid medium containing the disinfected contact lens is needed to enable safe and comfortable wear of the disinfected contact lens. Liquid media (not including the hydrogen peroxide contained therein) used to disinfect contact lenses should be substantially isotonic and ophthalmically acceptable so as to reduce the chances of problems caused by placing the disinfected lenses in the wearer's eyes.
Aqueous hydrogen peroxide-containing solutions currently in use as contact lens disinfectants include relatively high concentrations of hydrogen peroxide, e.g., on the order of 3% (w/v). Such high hydrogen peroxide concentrations are used so that the contact lens can be disinfected in a reasonable period of time. Of course, the more residual hydrogen peroxide remaining after lens disinfecting, the more difficult and time consuming the problem of destroying this residual hydrogen peroxide. It would be advantageous to provide a contact lens disinfecting system in which reduced amounts of hydrogen peroxide can be employed.
Associated with the problem of hydrogen peroxide destruction in contact lens disinfection systems are the problems of easy use and user compliance. To enhance user compliance and ease of use, several efforts have focused on one-step disinfection and hydrogen peroxide destruction. In this regard, various time release tablets containing a core tablet including a hydrogen peroxide destroying component, and having a delayed release coating on the core tablet have been suggested.
International Patent Publication No. WO 86/05695 discloses a contact lens disinfecting agent which includes a hydrogen peroxide precursor, e.g., sodium percarbonate, a hydrogen peroxide inactivating agent, such as ene-diols and sulfurous acid derivatives, in delayed release form, and a color change indicator to indicate the inactivation of the disinfecting agent. The inactivating agent is provided in delayed release form so that after the composition has been added to water, and the contact lens has been added to the mixture, the disinfecting agent has sufficient time to disinfect the contact lens before release of the inactivating agent.
Rosenbaum et al U.S. Pat. No. 4,473,550 discloses sterilizing contact lenses using a combination of a peroxidase, hydrogen peroxide and a donor molecule, such as a phenylethylamine, benzoic acid, salicyclic acid and para-aminobenzoic acid. Kessler et al U.S. Pat. No. 4,588,586 discloses disinfecting contact lenses using a combination of a peroxidase, hydrogen peroxide and a source of donor molecules including ascorbic acid. This latter patent teaches that the donor molecules supply electrons which the peroxidase donates to hydrogen peroxide. Both patents teach that it is essential to employ a peroxidase as part of the disinfectant composition. It would be beneficial to provide contact lens disinfectant composition which has a reduced number of constituents, and/or does not rely on an intermediate enzymatic activation of hydrogen peroxide.
Nelson et al U.S. Pat. No. 4,490,389 discloses a method for a sterilizing hydrophilic (soft) contact lens by contacting such a lens with a composition having a pH between 6 and 9, and containing 0.01 to 0.03 weight percent of an ene-diol compound, such as ascorbic acid, and between 0.1 and 25 ppm copper ion in solution. The Nelson et al patent strongly implies that other disinfectants, such as hydrogen peroxide, which tend to accumulate on or in hydrophilic contact lens are not included in this composition. The system of Nelson et al is relatively slow in sterilizing or disinfecting contact lens, and is of little value in cleaning the lens, e.g., of protein-based debris.
Ericsson et al U.S. Pat. No. 3,065,139 discloses anti-infectant topical preparations which include a percarbonate, an ene-diol compound and ions of metals of atomic numbers 25 to 30, i.e., Cu, Fe, Mn, Ni, and Co. This patent does not disclose disinfecting contact lenses, the use of a buffer component to control pH or the use of any oxidizer other than percarbonate.
Verachtert U.S. Pat. No. 4,311,598 discloses treating municipal sewage or effluents from paper or food processing industries with a combination of hydrogen peroxide, a soluble copper salt and an autoxisable reducing agent, such as ascorbic acid or sodium sulphite. This patent does not disclose disinfecting contact lenses, any ophthalmic application, or the use of a buffer to control pH. For example, the Verachtert patent is not concerned with substantially isotonic solutions, which are important to use in ophthalmic applications, such as disinfecting contact lenses.
There continues to be a need for a contact lens care system which rapidly and effectively disinfects, and preferably cleans, a contact lens so that the disinfected lens can be safely and comfortably worn.